Composite Cutting Tool

ABSTRACT

A laser beam is directed onto a bonding surface of a steel tool body to form a molten melt pool. Particles of high speed steel alloy are flowed into the melt pool and melt in the melt pool. The laser beam is moved along the bonding surface to form solid lines of high speed steel laser cladding metallurgically bonded to the cutter portion at the bonding surface and to each other. The cladding is abraded to form the cutting edge of a composite cutting tool.

This is a division of U.S. application Ser. No. 09/247,470 Feb. 3, 1999now U.S. Pat. No. 6,146,476.

FIELD OF THE INVENTION

The invention relates to cutting tools and methods of making cuttingtools.

BACKGROUND OF THE INVENTION

Cutting tools cut selected material from workpieces during machiningoperations. Examples of cutting tools include twist drills, router bits,reamers, broaches, end bores, counter bores, milling cutters and endmills. Cutting tools may cut any material including metal, wood, stone,plastic, composites, fiberglass, and the like.

Cutting tools have a tool body having a mounting portion for mounting ina machine tool and a cutting portion. The cutting portion typicallyincludes cutters away from the mounting portion. Cutters have exposedcutting edges at their outer edges. Moving the tool body forces thecutting edges into the workpiece, cutting away material and removing thecut material from the workpiece.

A cutting tool operates under extreme conditions. Large forces and highpressures are generated during cutting. The cutting edges often becomered-hot. Cutting tools may be sprayed with liquids for cooling or to aidcutting. The workpiece may be made from a hard or highly abrasivematerial that rapidly dulls the tool's cutting edges.

Cutting tools must be both hard and tough. Cutting edges should be ashard as possible to cut into the workpiece and resist dulling. Thecutting edges should also be heat resistant to maintain cutting abilityand not wear excessively at high temperature. Yet the tool body needs tobe rigid and tough. To assure accurate cuts, the tool body must notexcessively bend or flex during machining. The tool mounting portionmust be sufficiently tough to be held by a machine tool and to resistbreakage. If the tool breaks an expensive workpiece may be destroyed,production time is wasted, and operator safety may be at risk.

Cutting tools are conventionally made from tool steel or high speedsteel bodies. Special alloy steels are used. The steel is sufficientlyhard to form effective cutting edges, yet is sufficiently tough to beheld by the machine tool and not break during cutting. The maximumhardness of steel cutting tools is limited. Increasing the hardness ofthe steel makes the steel more brittle and reduces toughness. Thehardness of the steel cutting edges is limited because the steel toolbody must not crack or break.

To overcome the compromise between hardness and toughness necessary withsteel cutting tools, composite cutting tools have been developed. Theseinclude a tool body with cutters fixed to the tool body. The cuttingedges of the tool are formed on the cutters. The cutters are made from ahard, temperature-resistant material and the tool body is made from atough, and less expensive low carbon steel. A composite cutting tool mayinclude a tough, durable tool body carrying hard, temperature-resistantcutters. Composite cutting tools can cut through harder materials morequickly and for a longer time without dulling than non-composite steelcutting tools.

One known composite cutting tool includes a steel tool body with a hardplated coating. The coating usually covers the entire cutting edgeportion of the tool. Another known composite cutting tool includescutters made with hard inserts brazed or mechanically fastened to asteel tool body. The inserts are sharpened to form the cutting edges.

Known composite cutting tools have disadvantages. Plated tools have verythin coatings. The coating usually ranges from two ten-thousandths of aninch (0.0002 inch) to five thousandths of an inch thick (0.005 inch).The coating is so thin that pregrinding removes the plating so the toolcannot be resharpened. The entire cutter area is plated, wastingexpensive plating material. Brazing or mechanical fastening of cuttersto the tool body is time consuming, labor intensive, and requiresexpensive machining of the tool body. The brazed joint between thecutter and the tool body is prone to fail during cutting, destroying thetool, potentially destroying the workpiece along with it, and riskingoperator injury.

Thus, there is a need for an improved cutting tool. The cutters shouldbe bonded securely to the tool body, and be sufficiently thick to allowthe cutting edges to be finished ground when manufactured and to beresharpened. The tool body should be made from relatively inexpensivebut tough metal which can be reliably held by a machine tool and doesnot crack or break during use.

SUMMARY OF THE INVENTION

The present invention is directed to an improved cutting tool having aninexpensive low carbon steel or low grade high speed steel body and highspeed steel cutters. The cutters are integrally bonded to the tool bodyand can be resharpened when dulled. The cutters may be a compositehaving a high speed steel matrix surrounding particles of highlyabrasive materials including diamonds, and tungsten and titaniumcarbides. High speed steel cutter bodies without abrasive particles maybe hardened. Expensive machining of the tool body to receive the cuttersis not required and the improved cutting tool makes efficient use ofmaterials.

An integral cutting tool having features of the present inventionincludes a tool body having a mounting portion for being mounted in amachine tool and one or more cutters formed from a body of claddingmaterial metallurgically bonded to the tool body. Cutting edges areformed in the cladding.

The cladding material is joined to the tool body using a claddingmachine. A laser beam impinges the tool body and cladding powder isflowed onto the impingement area. The laser beam melts the claddingpowder and forms a pool of molten cladding material. The laser beamtraverses the tool body, moving the impingement area and depositing aline of cladding on the tool body to form a cutter. Molten cladding leftbehind the moving laser beam solidifies and is metallurgically bonded tothe tool body. The cladding is made typically from powdered high speedsteel alloy. Particles of very hard materials may be added.

Laser bonded high speed steel cladding is not hard. The cladding is in asemi-hard condition. In order to harden the cladding it is necessary tofully anneal the cladding and then heat treat the cladding to harden thecladding. After heat treating, the hardened cladding is machined,conventionally using an abrasive wheel, to a desired shape and a cuttingedge is formed. The mounting portion of the tool is not hardened andretains its desired toughness.

Where the cladding includes abrasive particles, the cladding need not beannealed and heat treated. Rather, this cladding is hard, is machined tothe desired dimension and is provided with a desired cutting edge,typically using an abrasive wheel.

Integral cutting tools with clad cutters have a number of advantagesover conventional cutting tools. The cutters are metallurgically bondedto the tool body and do not separate during cutting. The cutters aresufficiently thick to permit resharpening. The tool body does notrequire special machining to receive and hold the cutters. The claddingis deposited only where the cutters are needed, making efficient use ofcladding materials. The mounting portion is tough, easily held andresists breakage.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings illustrating the invention, of which there are sixsheets and eight embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an expansion reamer in accordance withthe present invention;

FIG. 2 is a sectional view of the working end of the expansion reamer ofFIG. 1;

FIG. 3 is a perspective view of a portion of the working end of theexpansion reamer of FIG. 1;

FIG. 4 is an enlarged vertical sectional view through a cutter and landof the expansion reamer of FIG. 1;

FIG. 5 is an axial sectional view of the cutter and land shown in FIG.4;

FIG. 6 is a perspective view of the tool body of the expansion reamer ofFIG. 1 prior to cladding the tool body;

FIG. 7 is similar to FIG. 3 but with side-by-side lines of claddingprior to forming cutters of the expansion reamer;

FIG. 8 is a vertical sectional view of the tool blank shown in FIG. 7;

FIG. 9 is an enlarged end view of a land with the side-by-side claddinglines of FIG. 7;

FIG. 10 is a sectional view through a land of the tool body of FIG. 6illustrating laser cladding the land;

FIG. 11 is a an enlarged vertical sectional view through a cutter andland of a second embodiment expansion reamer, the cutter formed fromsuperimposed layers of side-by-side lines of cladding;

FIG. 12 is a partial view of a milling cutter in accordance with thepresent invention;

FIG. 13 is a partial view of a broach in accordance with the presentinvention;

FIG. 14 is a view of a center drill in accordance with the presentinvention;

FIG. 15 is a view of an end mill in accordance with the presentinventions;

FIG. 16 is a view of a twist drill in accordance with the presentinvention;

FIG. 17 is a view of a non-expansion reamer in accordance with thepresent invention; and

FIG. 18 is a view of a counter bore in accordance with the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 and 2 illustrate a composite expansion reamer 10 in accordancewith the present invention. Reamer 10 is used for enlarging or finishingdrilled holes. Reamer 10 includes a generally cylindrical, elongate toolbody 12 having longitudinal valleys or flutes 14 between longitudinallands 16. Integral cutters 18 are formed from cladding material andmetallurgically bounded to the tops of the lands. Expansion slots 20 areformed in the bottoms of valleys 14. A tapered mandrel 22 is threadedinto a threaded bore 24 of tool body 12 to set the diameter of thefinished hole. The expansion of the reamer is exaggerated in FIG. 2.

FIGS. 3-5 illustrate cutters 18 bonded to tool body 12. Each cutter 18is bonded to a land 16. Cutters 18 are made from bodies of hard claddingmaterial particularly suited for cutting. A cutting edge 26 is formed orprofiled on each cutter. Radial outer surfaces 28 of cutters 18 can berelieved in a conventional manner to properly dimension the reamer.

FIG. 6 illustrates tool body 12 prior to bonding cutters 18 to lands 16.Tool body 12 is made of inexpensive, tough and relatively soft lowcarbon steel alloy or low grade high speed steel alloy. Low carbon steelalloy has a carbon content of about 0.6 percent or less. Low grade highspeed steel alloy has a carbon content greater than the carbon contentof low carbon steel alloy and less than about 0.9 percent. Low gradehigh speed steel alloy generally contains a low concentration of alloyconstituents such as molybdenum, vanadium, chromium, nickel and thelike.

The body 12 includes a mounting portion or shank 30 at one end of thebody and a cutting portion 32 at the other end of the body. The cuttingportion include lands 16 and bonding surfaces 34 on the tops of lands 16for bonding cutters 18 to tool body 12. Mounting portion 30 is adaptedto be held in a machine holder (not shown) in a conventional manner.

Each cutter 18 is formed from a body of cladding 36 metallurgicallybonded to surface 34 of a land 16. Cladding 36 is bonded to surface 34using methods described below. FIGS. 7-10 illustrate cladding 36 bondedto surfaces 34. Cladding 36 typically has a thickness 38 of betweenabout 0.020 inches to 0.060 inches. The thickness of cladding shown inthe drawing is exaggerated for clarity. Preferably cladding 36 issufficiently thick to allow resharpening of the subsequently formedcutter 18. A minimum cutter thickness 40 of between about 0.010 inchesto 0.020 inches is generally required to allow resharpening of a cutter.See FIG. 4.

FIG. 10 illustrates providing of bonding surface 34 with cutter cladding36. A cladding machine 42 includes a laser light beam source 44, aninert gas tube source 46, a cladding powder delivery tube 48, and anabrasive delivery tube 50 for crushed diamonds or tungsten or titaniumcarbide particles. Cladding machine 42 may be a Model HP-115 CL CNCCladding System available from Huffman Corporation, of Clover, S. C.

Cladding 36 is bonded on each bonding surface 34. Laser beam source 44generates a laser beam 52 that impinges against surface 34, defining aimpingement area 54 on surface 34. Laser beam 52 heats area 54 to a hightemperature between about 3,600° F. and 4,200° F. Inert gas tube 46flows an inert gas, for example argon, over the laser heated impingementarea 54 to prevent oxidation. Cladding powder delivery tube 48 flows astream of cladding particles 56 onto laser impingement area 54. Deliverytube 50 may flow a stream of abrasive particles 58 onto laserimpingement area 54. Laser beam 52 melts cladding particles 56 and thetop of surface 34 to form a melt pool 60 of molten material withabrasive particles 58, if provided, in the pool. Subsequent claddingpowder and abrasive particles are directed into the pool. The beam andtubes are moved along the land 16.

Movement of laser beam 52 along land 16 causes the laser impingementarea 54 to move along bonding surface 34, and moves the molten pool 60along with it. The molten cladding material, melted material fromsurface 34 and optional abrasives particles left behind cool,metallurgically bond with the underlying tool body portion 62 andsolidify to form a line of cladding 64. The fusion of the claddingmaterial and tool body portion 62 forms an extremely strongmetallurgical bond 66 that permanently bonds the cladding 64 to toolbody 12.

The high speed steel particles delivered to the impingement area meltinto pool 60. The abrasive particles, if provided, do not melt in thepool. The molten pool is comprised almost entirely of melted high speedsteel which mingles with the melted low grade steel from bonding surface34. The lower grade bonding surface steel defuses into the melted highspeed steel and has a decreasing concentration away from surface 34. Theportion of the cladding away from the surface 34 is essentially entirelyhigh speed steel. The cladding material cools to form a cladding line 64which is typically generally cylindrical, up to 0.060 inches thick and0.060 inches wide and extends above the bonding surface 34 of land 16.The width and thickness of cladding line 64 can be adjusted to meetdesign requirements. The path of cladding line 64 is defined by themovement of laser beam 52. As shown in FIGS. 7-9, two cladding lines 64are formed on and extend longitudinally along land 16. The lines aremetallurgically bonded to the land and to each other. In otherembodiments, cladding lines 64 may be curved or may include straight andcurved portions, depending upon the shape of the supporting land.

Laser beam 52 follows paths along the bonding surface 34 to clad theentire surface with joined, side-by-side lines of cladding 64. As shownin FIG. 9, cladding lines 64 are spaced sufficiently close together sothat the total cladding has sufficient size to subsequently form acutter 18. The path and number of cladding lines 64 can vary dependingon the desired shape of the cutter. For example, a smaller diameterreamer may require only one cladding line 64 to form a cutter. A largerdiameter reamer may require three or more side-by-side cladding linesfor each cutter.

If desired, cladding lines may also be superimposed and metallurgicallybonded to one another to increase the cladding thickness. FIG. 11illustrates a cutter 68 formed on land 70 with cladding 72 that includestwo superimposed layers of side-by-side lines of cladding 74. Thecladding is shown in phantom lines. Multi-line cladding is free of voidsto assure forming a continuous cutting edge. Tool body 12 is a heat sinkand solidifies molten cladding quickly. Three layers of cladding havebeen clad on a tool body without having to pause to cool depositedcladding before adding another layer. If a fourth or additional layer ofcladding is required, the previously deposited cladding layers should beallowed cool to about room temperature before applying the additionalcladding layer. It is believed that as cladding layers are superimposedon one another, the tool body becomes less effective as a heat sink.Cooling limits thermal distortion of the deposited cladding layers. Lessheat generated by the laser beam flows into the tool body and remainingheat remains in the cladding. The likelihood of permanent thermaldeformation of the cladding increases as heat is retained in thecladding. Cooling a preceding cladding layer allows adding a new layerand more heat to be stored in the cooled cladding without thermaldeformation. The number of cladding layers that can be clad on the toolbody before cooling is required will vary with the size of the tool bodyand type and size of the cladding.

During cladding, the high speed steel particles forming cladding 64 aremelted and then cooled, as described, forming a layer of heat treatablehigh speed steel alloy metallurgically bonded to the tool body. Ifabrasive particles are added to the cladding during bonding then theseparticles harden the cladding, which serves as a matrix holding theparticles, and it is not necessary to harden the cladding proper. Theabrasive particles in the cladding provide the hardness required forcutting. Tool bodies with cladding containing abrasive particles may befinished to desired shape as shown in FIG. 11 after cladding. Abrasivewheels are used to shape the lines of cladding and form two surfacesintersecting at a sharp cutting edge.

Cladding may be formed without abrasive particles. In this case, theapplied cladding is in a semi-hard condition at about 25 to 20 RockwellC and is unsuitable for cutting. Tools with this cladding must be heattreated to harden the cladding. Heat treating is performed by firstannealing the cladding to return the alloy to its base metallurgy. Thecutting portion 32 is also annealed. Then, the cladding and cuttingportion are heat treated to harden the cladding.

One way of annealing applied cladding is to place the cutting portion ofthe clad tool in a molten boride salt maintained at a temperature ofabout 1,700° F. for about two hours. Then, the portion is slowly cooledby reducing the furnace temperature to about 1,300° F. The tool is thentransferred to boride salt at about 1,000° F. When the part is cooled to1,000° F. the temperature is below the transfer range and the claddingis acceptably soft and in condition to be hardened by a conventionalheat treating process. The heat treating process used depends upon thenature of the high speed steel alloy in the cladding and isconventional. The cutting portion may be heat treated. After thecladding has been hardened by heat treating, the cladding is shaped,preferably by an abrasive wheel to form the desired cutting edge. Themounting portion of the tool is not heat treated and maintains itsdesired toughness.

Cladding may be used to repair a cutting tool where a cutting edge hasbeen broken or chipped away. In such an application, an appropriatedepth cladding is laser applied to the broken away portion of thecutting tool sufficient to replace the broken away metal as previouslydescribed. Abrasive particles may be added as required. If particles arenot added, then the cladding is fully annealed and heat treated asdescribed. The cladding with abrasive particles or heat treated claddingwithout abrasive particles in then shaped by a wheel to form a cuttingedge.

Applied cladding formed from particles of high speed steel is semi-hard,having a hardness of about 25-30 Rockwell C. When fully annealed, thecladding has a reduced hardness equivalent to that of low carbon steel,about 20 Rockwell C. Heat treating of the fully annealed claddingincreases the cladding hardness to about 63 to 68 Rockwell C, dependingupon the alloy of the cladding and the nature of the heat treatingprocess.

Cladding containing carbide particles may have a hardness as great as1,500 to 2,500 Vickers, which is considerably greater than 68 RockwellC. Cladding containing diamond particles is harder than claddingcontaining carbide particles.

Operation of expansion reamer 10 will now be described. Shank 30 isconventionally mounted in a machine tool. The machine tool rotatesexpansion reamer 10 about the reamer's longitudinal axis. Reamer cuttingedges 26 are spaced from the axis and define a cutting diameter of thereamer. Cutting portion 32 of the expansion reamer is inserted into aroughly drilled hole of a workpiece. The hole has an inside diameterless than the cutting diameter of the reamer. As the reamer is movedaxially into the hole, cutting edges 26 cut material from the workpieceto produce a finished hole.

The diameter of the finished hole produced by expansion reamer 10 may beadjusted by mandrel 22 in a conventional manner. Tightening taperedmandrel 22 in bore 24 forces cutting portion 32 of tool body 12 to bulgeradially outwardly. Lands 16 and cutters 18 assume a convex shape asshown in FIG. 2 where the curvature is exaggerated. The maximum outerdiameter at the cutting edges 26 establishes the cutting diameter ofcutting portion 32 and the finished diameter of the hole.

As cutters 18 wear, the cutting diameter of cutting portion 32decreases. The diameter of the finished hole decreases. To compensatefor cutter wear, mandrel 22 is further threaded into tapered bore 24until the outer diameter of work portion 32 expands and returns to thedesired finish diameter.

A conventional non-composite expansion reamer is formed from solid highspeed steel. The steel is typically heat treated to a hardness of about63 Rockwell C to 65 Rockwell C. In use, heat treated steel becomesbrittle and loses toughness. A non-composite expansion reamer issusceptible to cracking from the forces exerted by the mandrel on thebrittle steel.

An expansion reamer made in accordance with the present inventionpreferably has a mounting portion made from a tough, ductile steel. Theportion is sufficiently tough to withstand impact forces that wouldcrack a high speed steel cutting tool, and preferably can becase-hardened as necessary. Preferred body steels include low carbonsteels such as Nos. 4140, 1018, 1020 and the like. For example, shank 30is preferably case-hardened to a hardness of between about 20 to 23Rockwell C. Case-hardening hardens only the surface of shank 30 and doesnot reduce the toughness of tool body 12. Low grade tool steel may alsobe used.

The cutters are formed from high speed steel alloy powder. Grades M-2,M-7 and M-42 alloy powder may be used to make cladding. The hardness ofthe cutters is not limited by the toughness of the tool body. Thecutters can be harder than the cutters of a conventional expansionreamer. The improved expansion reamer can cut more quickly yet expand toa greater diameter and compensate for greater cutter wear than can aconventional expansion reamer.

Cutting edges 26 of expansion reamer 10 are located entirely alongcutters 18. The entire cutting edge need not be formed from cladding.Cutting edges located in high wear zones can be formed on cladding inaccordance with the present invention. Cutting edges in less demandingwear zones can be formed on the tool body itself in a conventionalmanner.

FIGS. 12-17 illustrate other cutting tools with cladding on cuttingportions of the tool. Each composite cutting tool includes a preformtool body having a mounting portion for mounting the tool in a machinetool and a cutting portion with one or more laser bonded cutters aspreviously described. Cutting edges are formed on the clad cutters.

FIG. 12 illustrates a portion of a milling cutter 76 with a generallydisc-shaped tool body 78 having an inner radial mounting portion 80 andan outer radial cutting portion 82. Mounting portion 80 surrounds anaxis of rotation of milling cutter 76. Cutting portion 82 extends aroundmounting portion 80. Clad cutters 84 are located at the outer diameterof milling cutter 76 and are spaced around the outer circumference ofmilling cutter 76. Mounting portion 80 includes an arbor hole 86 and akeyway slot 88 for mounting milling cutter 76 to an arbor of aconventional milling machine. In use, the arbor rotates milling cutter76 about the arbor's rotational axis for cutting a workpiece.

FIG. 13 illustrates a portion of a broach 96 with an elongate tool body98 having a mounting,portion 100 at one end and a cutting portion 102 atthe opposite end. Longitudinally spaced cutters 104 are metallurgicallybonded to cutting portion 102. The cutters are like the previouslydescribed cutters and are bonded and shaped as described. Mountingportion 100 includes a conventionally shaped tang (not shown) thatextends longitudinally away from cutting portion 102 for mounting broach96 in a collet of a conventional broaching machine. In use, a broachingmachine moves broach 96 along the longitudinal axis of the broach forenlarging or smoothing a work part.

FIG. 14 illustrates a center drill 106 having an elongate tool body 108including a center mounting portion 110 and an oppositely extendingcutting portion 112, 114 at each end. Cutters 116, 118 are bonded tocutting portions 112, 114 and shaped as. previously described. Mountingportion 110 includes a cylindrically shaped shank 120 for mountingcenter drill 106 in the chuck of a conventional drill press. One end ofcenter drill 106 is inserted in the chuck and forms a portion of shank120 held by the chuck. The other end of center drill 106 extends fromthe chuck. In use, the drill press rotates center drill 106 about thedrill's longitudinal axis for drilling a hole in a workpiece. Centerdrill 106 can be reversed in the chuck so that the cutters of the drillcan be swapped after wear. If desired, one cutting portion 112, 114 andbonded cutters 116, 118 can be eliminated.

FIG. 15 illustrates an end mill 122 having an elongate tool body 124including a mounting portion 126 on one end and a helical cuttingportion 128 on the opposite end. Cutters 130 of the type described arebonded to cutting portion 128 at the end of tool body 124 and extendradially from the longitudinal axis of end mill 122. Mounting portion126 includes a shank 132 for mounting end mill 122 in a holder of amilling machine. In use, the milling machine rotates end mill 122 aboutthe mill's longitudinal axis for removing material from a surface of aworkpiece. In some embodiments, cutting portions can be formed on eachend of the end mill similar to center drill 106.

FIG. 16 illustrates a twist drill 134 having an elongate tool body 136including a mounting portion 138 on one end and a helical cuttingportion 140 on the opposite end. Cutters 142 of the type described arebonded to cutting portion 140. Mounting portion 138 includes acylindrical shank 144 for mounting twist drill 134 in a chuck of a drillpress. In use, the drill press rotates twist drill 134 about the drill'slongitudinal axis for drilling a hole in a workpiece.

FIG. 17 illustrates a non-expansion reamer 146 having an elongate toolbody 148 including a mounting portion 150 on one end and a cuttingportion 152 on the opposite end. Cutters 154 as described are bonded tocutting portion 152. Mounting portion 150 includes a cylindrical shank156 for mounting reamer 146 in a chuck of a drill press. In use, thedrill press rotates reamer 146 about the reamer's longitudinal axis forfinishing a hole in a workpiece.

FIG. 18 illustrates a counter bore 158 having an elongate tool body 160including a mounting portion 162 on one end and a cutting portion 164 onthe opposite end. Cutters 166 as described are bonded to cutting portion164. Mounting portion 162 includes a cylindrical shank 165 for mountingcounter bore 158 in a chuck of a drill press. In use, the drill pressrotates counter bore 158 about the bore's longitudinal axis forcounterboring a workpiece, i.e., boring the end of a hole to a largerdiameter.

Composite cutting tools with clad cutters have a number of additionaladvantages over conventional composite cutting tools. Very accuratenumerically controlled cladding machines can automate cladding of thetool body. Expensive machining of the tool body for receiving inserts iseliminated. Conventional steel cutting tools can be used as-is for thetool body, allowing existing non-composite steel cutting tools to betransformed into improved clad laser clad cutting tools.

While I have illustrated and described a preferred embodiment of myinvention, it is understood that this is capable of modification, and Itherefore do not wish to be limited to the precise details set forth,but desire to avail ourselves of such changes and alterations as fallwithin the purview of the following claims.

I claim:
 1. A composite cutting tool comprising: (a) a tool body formedfrom a metal having a first hardness, said body including a mountingportion and a cutting portion having one or more bonding surfaces; and(b) one or more cutters, each cutter formed from metal laser claddinghaving a second hardness greater than said first hardness, each cutterjoined to the tool body at a bonding surface, a solidified melt pool ateach bonding surface, each pool including a mixture of said tool bodymetal and said laser cladding metal and having a greater concentrationof said tool body metal adjacent the mounting portion than away from themounting portion, the laser cladding in each cutter including two formedsurfaces intersecting at a cutting edge.
 2. The tool as in claim 1wherein said formed surfaces are abraded.
 3. The tool as in claim 2including a plurality of metal cutters formed from metal laser cladding,each cutter including a cutting edge, all of said cutting edges facingin the same direction.
 4. The tool as in claim 3 wherein the mountingportion is cylindrical and said cutting edges are spaced around themounting portion.
 5. The tool as in claim 3 wherein the mounting portionis flat and the cutting edges are spaced on one side of the mountingportion.
 6. The tool as in claim 3 wherein the tool body comprises oneof: a center bore, a center drill, a twist drill, an end mill, anexpansion reamer and a non-expansion reamer.
 7. The tool as in claim 2wherein each cutter includes a plurality of lines of laser cladding anda metallurgical bond between adjacent lines of laser cladding.
 8. Acomposite rotary cutting tool comprising: (a) a rotary metal tool bodyformed from a first alloy of either a low carbon steel or low grade highspeed steel, the tool body having a rotary axis and including acylindrical mounting portion on the axis adapted to be held by a chuck,the mounting portion having a first hardness, and a cutting portionaxially spaced from the mounting portion and including one or morebonding surfaces each extending along the axis; and (b) one or moreshaped metal cutters, each cutter integrally joined to the cuttingportion at a bonding surface and formed from high speed steel alloylaser cladding having a second hardness greater than said firsthardness, a metallurgical bond between said cladding and the cuttingportion at the bonding surface, each cutter including two abradedsurfaces extending along the axis and intersecting at a cutting edgeextending along the axis, each cutting edge facing in the samecircumferential direction around the axis.
 9. The tool as in claim 8wherein cutters have a hardness greater than 63 Rockwell C and saidmounting portion has a hardness of between about 20 to about 23 RockwellC.
 10. The tool as in claim 8 including abrasive particles in the lasercladding.
 11. The tool as in claim 10 wherein said particles are formedfrom either a carbide or diamonds.
 12. The tool as in claim 8 includinga plurality of a elongate metal cutters located radially outwardly ofthe axis, spaced around the axis and extending along the axis, each suchcutter including layers of a plurality of elongate lines of lasercladding extending along the length of one cutter, first metallurgicalbonds between the lines of cladding in the layer adjacent the bondingsurface and the bonding surface, second metallurgical bonds between thelines of cladding in each layer of lines, and third metallurgical bondsbetween the lines of cladding in adjacent layers of lines, each cutterbounded by said two abraded surfaces and by a third abraded surface awayfrom the cutting edge.
 13. The tool as in claim 12 wherein one of saidabraded surfaces and the third surface form extensions of surfaces onthe cutting portion adjacent a bonding surface.
 14. The tool as in claim13 wherein the thickness of each cutter above the adjacent mountingsurface is equal to or greater than about 0.01 inch.
 15. The tool as inclaim 8 wherein said first hardness is between about 20 and about 23Rockwell C, said second hardness is greater than about 63 Rockwell C andthe thickness of the cladding in each cutter above the bonding surfaceis equal or greater than about 0.01 inch.
 16. A composite cutting toolcomprising: (a) a metal tool body formed from a first alloy of either alow carbon steel or low grade high speed steel, the tool body includinga mounting portion adapted to be held by a machine tool, and having afirst hardness, and a cutting portion including one or more bondingsurfaces; and (b) one or more metal cutters, each cutter comprising abody of laser cladding and including at least a first line of lasercladding extending along a bonding surface, said laser cladding formedfrom a high speed steel alloy having a second hardness greater than saidfirst hardness, a solidified melt pool at the bonding surface, thesolidified melt pool forming a first metallurgical bond between saidlaser cladding and the cutting portion, said metallurgical bondincluding a mixture of said first alloy and said high speed steel alloyand having a greater concentration of said first alloy adjacent themounting portion than away from the mounting portion, each cutterincluding two formed surfaces on the laser cladding and intersecting ata cutting edge.
 17. The tool as is claim 16 wherein each cutter includesa second line of laser cladding formed from said high speed steel alloyand extending along first line of laser cladding, a second metallurgicalbond between the first and second lines of laser cladding, and a thirdmetallurgical bond between said second line of laser cladding and thecutting portion.
 18. The tool as in claim 17 wherein each cutterincludes a third line of laser cladding formed from said high speedsteel alloy and extending along said first and second lines of lasercladding a distance above the bonding surface and including a fourthmetallurgical bond between said third line of laser cladding and eitheror both of said first and second lines of laser cladding.
 19. The toolas in claim 18 wherein said formed surfaces and cutting edges extendalong and generally parallel to said lines of laser cladding, at leastone of said formed surfaces extending along said third line of lasercladding.
 20. The tool as in claim 16 wherein said mounting portion hasa Rockwell C hardness of from about 20 to about 23 and said high speedalloy has a Rockwell C hardness greater than about
 63. 21. The tool asin claim 16 including abrasive particles in said high speed steel alloy,said alloy comprising a matrix for the particles, said cladding having ahardness greater than 1,500 Vickers.
 22. The tool as in claim 21 whereinsaid particles are formed from a carbide and said laser cladding havinga hardness of between about 1,500 and about 2,500 Vickers.
 23. The toolas in claim 21 including diamond particles in the laser cladding andsaid laser cladding having a hardness greater than about 2,500 Vickers.24. The tool as in claim 16 wherein said cladding has a thickness fromabout 0.01 inch to about 0.02 inch.
 25. The tool as in claim 16 whereinsaid tool body is rotary and defines a rotational axis, said mountingportion is cylindrical and extends along said axis.
 26. The tool as inclaim 25 wherein said tool body comprises a reamer, said cutting portionincludes a plurality of flutes and lands extending alternately aroundsaid axis away from the mounting portion, bonding surfaces on the lands,said metal cutters each extending along a bonding surface generallyparallel to said axis with a cutting edge located on one side of eachland, all of said cutting edges facing in one circumferential direction.27. The tool as in claim 26 including expansion slots in said tool bodylocated in said valleys between adjacent lands and including a mandrelengageable said lands to move the cutters radially outwardly.
 28. Thetool as in claim 16 wherein said tool body comprises one of a centerbore, a broach, a center drill, a twist drill, an end mill, an expansionreamer, and a non-expansion reamer.
 29. The tool as in claim 15 whereinsaid tool body comprises one of: a center bore, a center drill, a twistdrill, an end mill, an expansion reamer and a non-expansion reamer. 30.The tool as in claim 8 wherein each cutting edge extends helically alongand around the axis.
 31. The tool as in claim 8 wherein each cuttingedge extends parallel to the axis.
 32. The tool as in claim 8 whereineach cutter is free of voids and includes a plurality of lines of lasercladding and including second metallurgical bonds between adjacent linesof laser cladding.
 33. The method as in claim 32 wherein each cutterincludes layers of lines of laser cladding and third metallurgical bandsbetween cladding lines in adjacent layers.
 34. The tool as in claim 32wherein said second hardness is greater than about 63 Rockwell C. 35.The tool as in claim 32 including abrasive particles in the lasercladding.
 36. The tool as in claim 35 wherein said second hardness isgreater than about 1,500 Vickers.
 37. The tool as in claim 32 includingcarbide particles in the laser cladding.
 38. The tool as in claim 32including diamond particles in the laser cladding.
 39. The tool as inclaim 8 wherein said laser cladding includes a number of layers of linesof cladding, second metallurgical bonds joining said lines of lasercladding together and the cladding is free of voids.